It's really hard going from the marital income down to one. I've done it.
What I did and still do,
Always take coffee and water out with me, so no temptation to buy one, especially on the way into work
Packed lunch for work, everyday.
Set aside an amount for food shopping and order online, get a delivery saver pass. Or withdraw the cash and only use that if shopping in store.
Google is your friend if you need to purchase something, ie skincare, as you can price compare. Lookfantastic.com offer great discounts.
If you have an Amazon prime account you can read books for free on their kindle app, they're labelled "prime reading". Amazon are often cheaper for household cleaning items, look at the per ml/kg price. The big name brands that are listed first are usually the most expensive.
Whatever money you have left at the end of the week put aside into a separate account. £5 or £10 a week quickly grows!
Any potential purchase leave in the online basket for an hour, and then return, you may not need the item as much as you think you do.
Look through your bank statement for last month and see what subscription payments are going out, you may be paying for things twice, or not need any longer, ie if you have sky TV you don't need a separate Netflix account as it is included in the Sky TV package.
Good luck 🤞🏻